CVE-2026-102916
A reachable assertion in the illumos bhyve instruction emulator allows a guest to panic the host.
Does this matter?
Lower severity and a low EPSS score (0.12%). Track it; it rarely justifies an emergency change on its own.
Description
A reachable assertion in the illumos bhyve instruction emulator allows a guest to panic the host. When emulating a REP-prefixed MOVS or STOS instruction that accesses guest MMIO, vie_emulate_movs() and vie_emulate_stos() in usr/src/uts/intel/io/vmm/vmm_instruction_emul.c do not clear the VIES_REPEAT status flag on the final iteration. For MMIO regions emulated in the kernel (the local APIC, I/O APIC and HPET), the stale flag causes a VERIFY assertion in vie_advance_pc() to fail, and the host panics. A privileged user within a guest VM can issue a REP MOVS or REP STOS instruction against the local APIC page to cause a denial of service of the host and every other guest running on it. The flaw has existed since 2020 (illumos-gate commit e0c0d44e), and affects any illumos distribution prior to illumos-gate commit 696ecf8d.
- CVSS 4.0
- 6.8 MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.12% probability · 2th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-617
- Source
- 0ca53633-f0b5-4853-ba72-e0a2e62000d0
EPSS moved from 0.1% on 10 October 2026 to 0.1% on 26 October 2026.
References
- https://github.com/illumos/illumos-gate/commit/696ecf8debceed9dc33937d8c8e111e4aeebfdae
- https://illumos.org/issues/18491
- https://illumos.topicbox.com/groups/developer/T697a32b688807e56/cve-2026-102916-18491-bhyve-rep-prefix-instr-emulation-fumbles-flags
- http://www.openwall.com/lists/oss-security/2026/10/09/19
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.